1 // Copyright 2015 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_HEAP_SCAVENGE_JOB_H_ 6 #define V8_HEAP_SCAVENGE_JOB_H_ 7 8 #include "src/cancelable-task.h" 9 #include "src/globals.h" 10 11 namespace v8 { 12 namespace internal { 13 14 class Heap; 15 class Isolate; 16 17 // This class posts idle tasks and performs scavenges in the idle tasks. 18 class V8_EXPORT_PRIVATE ScavengeJob { 19 public: 20 class IdleTask : public CancelableIdleTask { 21 public: IdleTask(Isolate * isolate,ScavengeJob * job)22 explicit IdleTask(Isolate* isolate, ScavengeJob* job) 23 : CancelableIdleTask(isolate), isolate_(isolate), job_(job) {} 24 // CancelableIdleTask overrides. 25 void RunInternal(double deadline_in_seconds) override; 26 isolate()27 Isolate* isolate() { return isolate_; } 28 29 private: 30 Isolate* isolate_; 31 ScavengeJob* job_; 32 }; 33 ScavengeJob()34 ScavengeJob() 35 : idle_task_pending_(false), 36 idle_task_rescheduled_(false), 37 bytes_allocated_since_the_last_task_(0) {} 38 39 // Posts an idle task if the cumulative bytes allocated since the last 40 // idle task exceed kBytesAllocatedBeforeNextIdleTask. 41 void ScheduleIdleTaskIfNeeded(Heap* heap, int bytes_allocated); 42 43 // Posts an idle task ignoring the bytes allocated, but makes sure 44 // that the new idle task cannot reschedule again. 45 // This prevents infinite rescheduling. 46 void RescheduleIdleTask(Heap* heap); 47 IdleTaskPending()48 bool IdleTaskPending() { return idle_task_pending_; } NotifyIdleTask()49 void NotifyIdleTask() { idle_task_pending_ = false; } IdleTaskRescheduled()50 bool IdleTaskRescheduled() { return idle_task_rescheduled_; } 51 52 static bool ReachedIdleAllocationLimit(double scavenge_speed_in_bytes_per_ms, 53 size_t new_space_size, 54 size_t new_space_capacity); 55 56 static bool EnoughIdleTimeForScavenge(double idle_time_ms, 57 double scavenge_speed_in_bytes_per_ms, 58 size_t new_space_size); 59 60 // If we haven't recorded any scavenger events yet, we use a conservative 61 // lower bound for the scavenger speed. 62 static const int kInitialScavengeSpeedInBytesPerMs = 256 * KB; 63 // Estimate of the average idle time that an idle task gets. 64 static const int kAverageIdleTimeMs = 5; 65 // The number of bytes to be allocated in new space before the next idle 66 // task is posted. 67 static const size_t kBytesAllocatedBeforeNextIdleTask = 1024 * KB; 68 // The minimum size of allocated new space objects to trigger a scavenge. 69 static const size_t kMinAllocationLimit = 512 * KB; 70 // The allocation limit cannot exceed this fraction of the new space capacity. 71 static const double kMaxAllocationLimitAsFractionOfNewSpace; 72 73 private: 74 void ScheduleIdleTask(Heap* heap); 75 bool idle_task_pending_; 76 bool idle_task_rescheduled_; 77 int bytes_allocated_since_the_last_task_; 78 }; 79 } // namespace internal 80 } // namespace v8 81 82 #endif // V8_HEAP_SCAVENGE_JOB_H_ 83